give me the stars (and i'll give you the sun)
by itsclowreedsfault
Summary: The story of how Day and Night defied the rules of nature to discover each other's worlds, and ended up falling in love in the process.


When Katsuki lands at the top of the mountain, the last rays of sunlight are fading in the horizon.

Seconds after his feet touch the ground, he lets himself fall on the grass. It prickles his wings, making him shift uncomfortably for a few moments, the lethargy that comes with the end of the day wearing on his bones. Above him, the first stars have started to show.

Katsuki's eyes threaten to slide shut, but he struggles to keep them open.

"You're cutting it close," comes a voice from above him.

Katsuki cranes his neck to look at the figure standing a few feet from his left. Shouto's hair is still messy from waking up, but his wings are fully spread behind him, casting long shadows on the ground. With night only a few minutes away, his feathers look almost black, save for the spots of light that reflect off them when he moves.

Looking at Shouto's wings is what Katsuki imagines is like to look at the starry night sky; a reversed image of his own, painted with the oranges and reds of dawn. No matter how long they've known each other, the sight never ceases to take his breath away for a moment or two.

"You could've fallen asleep before making it here," Shouto continues, brow wrinkling in concern when all Katsuki does is snort.

"How do you know?" Fighting the tiredness in his body, Katsuki sits up, tearing his gaze away from Shouto to look at the city that spreads below them. "I bet I could fight it."

"Like you're doing now?"

Katsuki sways a little as he pulls himself to his feet. He feels it, deep inside him, whatever instinct is telling him that this is _wrong_ , that he should just give up and allow sleep to overtake him. It's the same instinct that plagues both of them, making sure their world is limited to the times of day they represent, sending Day to sleep when Night arrives and vice-versa, save for a few stolen moments in between.

Katsuki is fucking tired of listening to it.

"I'll show you," he mutters through gritted teeth.

Shouto considers this for a few moments before sighing and stepping beside Katsuki to join him in contemplation of the city. His wings brush Katsuki's when he widens them for flight, and Katsuki has to suppress the shiver it sends down his spine as he copies the movement.

"You sure about this?" Shouto asks.

Katsuki takes in the darkening sky, the colors already so different from what he's used to. The air thrums with a type of energy he's never felt before.

A thrill runs through his body.

"Try to keep up," he shouts behind his shoulder, not looking back before jumping into nothing, letting his wings carry him over the web of blinking lights of the city.

The sound of Shouto's reply is lost in the wind as they take to the night sky together.

* * *

There was a time when Day knew nothing of the night.

He could only guess, use his imagination to build from the scraps of information Night himself would share before Day's body was dragged into sleep. For a while, he'd been satisfied—but immortality is a long time to live knowing there's something waiting just out of your reach.

So Day defied the rules.

With Night by his side, he flew without fear into a world he'd never known—a world of artificial lights and deeper shadows, of quieting houses and awakening parties, of new and beautiful things that made him wish he could fight the pull of sleep forever.

He couldn't.

He fell, but Night was there to catch him when he did.

* * *

Katsuki takes a deep breath, and it feels like fire making its way down his lungs. He is used to the heat of the sun warming his skin, but this is nothing like it—his entire body burns feverishly hot. He struggles, hoping to escape the suffocating feeling, but hands hold him down, soothing touches pushing away the hair that's stuck to his skin with sweat.

Something cold, so _blissfully cold_ , touches his forehead, and Katsuki's eyes snap open.

"W-What," Katsuki croaks out, wincing at the raw scrape of his voice against his throat. "What the fuck are you doing?"

Shouto's face hovers above him. His hand halts midway through dragging a wet rag over Katsuki's forehead.

"Katsuki," he mutters. His eyes close, the hints of a smile tilting his lips. He lets the rag fall with a tired sigh. "Finally, you're awake."

"Oi, will you explain what the hell—"

Katsuki doesn't have a chance to finish his sentence. Shouto tumbles to the side, and by the time Katsuki has managed to scramble to a half-sitting position he's already curled up on himself, wings resting like patches of sky against the grass.

"You did fight it," he says, the jumbled words indicating he's about to fall asleep. "It was stupid of you."

It is only then that Katsuki notices the sun shining bright above them. There are no stars, no moon anymore—nothing of the night Katsuki has come to know, nor of the dawn he's used to seeing when he usually wakes up.

"How long was I out?"

Shouto snorts, bringing his arms close to his chest and tucking his hands under his head like a pillow.

"All… night. Plus a few hours."

"You idiot." Katsuki's heart beats fast, the remains of the fever leaving him shaky. It is one thing for him to push his own limits, but for Shouto to do it, to do it for _him_ , to the point where exhaustion is clear on his face, in his _voice_ — "I didn't ask you to take care of me."

But Shouto is already out, snoring softly, and Katsuki is left staring at him in frustration, cursing Shouto for being so fucking adorable when he sleeps that Katsuki can't possibly stay angry with him.

His gaze falls on the rag lying beside him. He remembers the gentle drag of it against his forehead, how nice it had felt to have Shouto's cool touch against his skin.

His heart beats a little faster, for reasons that have nothing to do with a fever.

* * *

Day and Night had known each other for as long as they could remember.

They were opposites, yet similar; forever stuck in the same endless cycle. However, there was something more mundane they shared other than wings to carry them and nature to bind them.

They were both stubborn.

Like Night had done, Day cared for him when he started shivering, reaping the results of his defiance against the rules. Day pushed through his own fatigue, pulling Night close and letting his wings cover him when Night's skin turned ice cold, the remaining heat of the fever in his own body a blessing for once.

One would think that this would be the end of it, with the consequences taking their toll on them—but it was only the beginning.

* * *

"There's a festival at the city tonight."

Katsuki doesn't answer, trying to feign sleep without succumbing to it. The bark of the tree digging into his back is a good distraction, but his thoughts still swirl in and out of focus, his body begging him to relax.

He wishes Shouto would just fucking _leave_ already so he can stop pretending.

"You'll draw blood if you keep digging your fingers into your knees like that."

Katsuki opens his eyes, releasing the grip he unconsciously had on himself. He winces a little at the sting. The soft material of his white pants is marked with indents of his nails; if he were to look, his skin would probably be marked, too.

"Shouldn't you be out of here by now?" Katsuki grumbles. They never stick to the mountain for long when they're awake, preferring to fly over the city instead—leave it to Shouto to decide to stay tonight of all nights.

Shouto extends a hand. Katsuki ignores it, standing up on shaky legs.

"You're staying awake tonight again, aren't you?" Shouto asks, letting his hand fall. He doesn't wait for an answer before continuing, "You remember what happened last time. I can't let you go flying off on your own."

"I wouldn't be that stupid."

"Are you sure about that?"

"Shut up, I didn't _ask_ for your help last time." Katsuki crosses his arms, leaning back against the tree. He can see the moon in the sky right above Shouto's head, and in the distance beyond the mountain's edge the lights of the city seem brighter than he remembers. "I'm not an idiot."

Katsuki truly hadn't planned to fly—he knew better than to do that alone, as much as he wished to take to the night sky again after that first time weeks ago. He didn't want Shouto to have to babysit him, though; if he was going to break the rules by his choice, he would face the consequences on his own.

Except, apparently, Shouto has different ideas.

"Like I said, there's a festival at the city tonight," Shouto says, shooting a brief glance backwards. "They set it up right at the foot of the mountain."

"I know about it." For the past couple of days, Katsuki had watched as the tents were built, had hovered above the unsuspecting humans as the air brimmed with their voices. "So what?"

"Festivals usually have a fireworks show." Shouto walks to the edge of the cliff, followed by Katsuki. To his surprise, Shouto sits down, crossing his legs and letting his wings rest closed behind him. "This is a good place to watch from."

For a few moments, Katsuki does nothing but stare, and Shouto holds his gaze with a neutral expression that tells Katsuki he's taking this seriously.

Shouto really does expect him to watch the fireworks with him.

"If you weren't Night, I'd say the sun fried your brain," Katsuki says. When Shouto doesn't react, he sits down with a huff beside him. "If the same happens as last time, you won't fucking push yourself to take care of me again. I can handle a fever."

"Okay," Shouto says with a nod.

He's too collected, his tone too neutral; Katsuki shoots daggers at him with his eyes but Shouto refuses to back down.

"You're lying, aren't you?" Katsuki says.

"You were lying about being asleep earlier. That makes us even."

It's not the same thing, and Shouto must be aware of that. Raising one of his knees, Katsuki leans his forearm on it, resting his chin there. "You're so fucking annoying."

Shouto doesn't let the insult faze him.

"Try not to fall asleep before it starts," is his only reply.

"I don't need you to tell me that."

They fall into a silence that is filled with the sounds of the city, with the echo of voices and music coming from the festival. Even if his gaze doesn't stray from the scenery below them, Katsuki can sense Shouto's presence; he's as part of the night as everything else, fitting effortlessly into the scenario just like Katsuki does when it's daytime.

Katsuki could choose to give up, allow sleep to overtake him and leave Shouto alone with his fireworks. He could plan better, try again some other night when Shouto won't stay behind with him, when it'll be just one and not two of them getting deeper into this mess—whatever this mess _is_.

But truth is, Katsuki has never liked the idea of giving up.

* * *

On the night colors painted the sky, everything changed.

When the fireworks started, Day didn't notice the way Night was looking at him instead of at the show unraveling before them.

When the fireworks ended and Night asked him what he thought, Day didn't say thank you, but there was a smile on his lips when he fell asleep leaning against Night's shoulder.

There were consequences—there always would be—but whether because they'd known what was coming or because the first time had made them stronger, the pain didn't seem as bad as before.

Or maybe it was only that they did not care for the price when what they gained in return felt worth it.

* * *

There's something freeing about the wind rushing past him as Katsuki flies as fast as he can. The city is nothing but a blur far below, small in contrast to the light blue sky stretching in front of him.

One look over his shoulder shows him that Shouto is catching up. With a sneer, Katsuki puts more strength into flapping his wings, trying to increase the distance between them. His eyes fixate on his goal—the large tree at the top of the mountain, getting closer with each passing moment.

With a shout, he reaches it, the gust of air that accompanies his flight rustling its leaves. Hovering over the tree, Katsuki turns around just in time to see Shouto come to a stop before him, hair tousled and breathing slightly erratic.

"Too slow," Katsuki says, grinning.

"We'll see who's slow when we race during nighttime," Shouto replies. He doesn't seem too disappointed about his defeat, lips turned upwards almost imperceptibly when his gaze move towards the city.

This isn't the first time Shouto sees it all during the day, but there's still wonder in his eyes every time. Even Katsuki, who is used to the light of the sun, finds he prefers the days when Shouto stays awake with him; his presence is thrilling, their races exhilarating, and somehow Katsuki's eyes seem to keep straying to him every time he stops policing himself.

Right now, Katsuki is so close he can see details in Shouto's wings he'd never noticed before. The feathers are a myriad of colors, a gradient of darkening blues that turn to purple that turn to black, the gradient so subtle it's no wonder Katsuki had never seen it under the darkness of the night. The glimmering dots ripple and bend with every movement of Shouto's wings.

"Katsuki?"

It's Shouto's voice that snaps Katsuki back to reality. His mouth is suddenly dry as his gaze moves to Shouto's face, over his scar, tracing the smooth skin of his cheekbones down to his lips.

Slightly parted. Red. Kissable.

Katsuki's heartbeat quickens—since when does he want to kiss Shouto? But he does. He wants to kiss him so much it leaves him at a loss for words, right there with the sun reaching its zenith over their heads, because Shouto is still looking at him with those fucking pretty eyes that are straying down to his mouth as well and—fuck _._

Before he realizes it, Katsuki has closed the distance between them, fingers threading through Shouto's hair to pull him down until their lips meet.

Shouto tastes like the cool night wind, and it's as addictive as the feel of it when Katsuki flies by his side. His eyes remain open for a few seconds, staring at Katsuki's own in shock, and Katsuki is about to pull back when Shouto's hands take hold of his shirt to press their lips together again, eyelids finally closing.

Katsuki lets his own fall shut, allowing the kiss to take over all of his senses.

* * *

Day and Night didn't mean to fall in love.

 _This is against the rules._

 _Fuck the rules. Not like we haven't been breaking them for a while now, right?_

It just happened.

* * *

Shouto's back arches beneath Katsuki's touch.

"Please," he mutters.

Katsuki ignores him, continuing to focus on the task of running his teeth between Shouto's shoulder blades, kissing and nibbling at the edge where wings meet skin. His hands hold Shouto's waist firmly to keep him from turning around.

Shouto reaches down to touch himself and Katsuki slaps his hand back to the tree he's braced against.

"Katsuki," Shouto pleads, voice cracking.

"Hmm." Katsuki smiles against Shouto's skin. There's no trace of sleepiness in Shouto despite the sun shining high above them; he squirms in Katsuki's hold, torn between pressing back against him and humping the air in search of friction he can't get.

Katsuki had never thought seeing Shouto like this would be so captivating. Beneath the morning light, his skin glistens with a layer of sweat, wings fluttering open in a ripple of dark blue and purple and black. Katsuki finally moves his lips away from his back to ghost over the feathers, letting his nose trail them lightly—Shouto's wings still fascinate him, so similar yet different from his own, so beautiful and sensitive to even the faintest touch.

Katsuki lets go of Shouto's waist, tangling his hand in Shouto's wings right above the junction with his back, tugging lightly on the feathers while pressing with the lower part of his fist.

Shouto's moan echoes in his ears, louder than it'd been before, any trace of patience gone as plea after plea falls from his lips.

"Fuck." Katsuki presses himself closer to Shouto's back, groaning as he grinds against his ass. It's his turn to whisper Shouto's name, not once letting go of his wings, imagining what it'd feel like to have _Shouto_ touching him like this instead.

Katsuki makes a mental note to ask him to do that next time.

"Katsuki, please—please, let me—"

Katsuki doesn't let Shouto finish speaking, reaching out to take his cock in one hand while keeping the other firmly massaging his wings. He is lost in the feeling of Shouto's skin, the sound of his voice as Shouto comes after nothing but a few strokes, trembling and completely wrecked.

For a few moments, they're both left breathing hard, Katsuki resting his head against Shouto's back. Out of the corner of his eyes, the shiny dots on Shouto's wings shimmer against the sunlight, blurring in and out of his vision.

When his heart has calmed down enough, Katsuki pulls back, ignoring the loss of friction on his aching cock as he turns Shouto around. He keeps one arm around his waist to steady Shouto while using his clean hand to push back the bangs that stick to his forehead.

Shouto blinks at him, slightly dazed.

"You okay?" Katsuki asks, worried that he might've pushed too far—Shouto's been awake for quite a few hours past the limit now.

"Tired," Shouto says, sounding a bit hoarse. He cleans his throat before speaking again. "But not about to black out, if that's what you're asking."

Katsuki sighs in relief, closing his eyes to enjoy the feeling of Shouto placing his hands on his back, tracing his spine. His body still burns hot, but if Shouto's this tired already, he doesn't want to risk pushing him any further.

He doesn't expect Shouto to suddenly dig his fingers into his wings, ripping out a moan from Katsuki's throat as a wave of pleasure spreads through his body.

"Shouto, what—Ah, fuck." Katsuki's breath turns labored again, hips snapping forward of their own volition.

Shouto's touch feels even better than he imagined.

"You're still hard," Shouto states.

Katsuki has to fight the urge to roll his eyes at the obvious statement. "I can deal with it. You should rest."

Shouto runs his hands down Katsuki's feathers, just barely scraping his nails as he makes his way down to his back. Katsuki's mind goes blank, hours of pent up tension nearly making him come on the spot. "What if I don't want to rest?"

Katsuki's protest dies on his tongue, replaced by a groan. He tries to focus on anything other than Shouto's hands, struggling to form a coherent sentence.

"Let me at least grab the lube," he gasps.

Shouto lets go of him with a confused expression. He watches as Katsuki disentangles himself to look through the mess of clothes they'd discarded earlier, wiping his hand on one of their shirts while he's at it.

"Did you _steal_ that from the humans?" Shouto eyes the bottle Katsuki brings back with him.

"Is _that_ what you're worried about?" Katsuki laughs as he cages Shouto against the tree again, pressing one kiss to his shoulder as he uncaps the lube. "I wasn't about to let you fuck me raw, and I am _not_ fucking _you_ raw, either. I don't want to hurt you."

Shouto opens his mouth as if to protest, but closes it without saying anything. There's softness in his gaze when he pulls Katsuki into a kiss, gentle lips turning slightly cold, his body pliant as Katsuki traces slippery fingers around his entrance.

It doesn't take long for them to be lost in each other again.

* * *

The problem with love is that it makes you reckless.

As much as they were aware of breaking the rules, Day and Night had still been careful at first. Weeks separated their encounters; they never stayed awake for too many days or nights in a row, and for a while that was enough.

Until it wasn't.

It wasn't only the splendor of the day or the beauty of the night they'd gotten to know; it was the presence of each other, the playful banter, the touches and kisses that only made them crave more. Soon, Day and Night forgot to be careful, forgot some limits are there for a reason and were never meant to be crossed.

They pushed, and pushed and pushed.

And it all broke apart.

It was dawn when they fell asleep, tangled with each other beneath the big tree on top of the mountain. For three days, they slept—and in the meantime, the world was plunged into chaos.

The eclipse baffled the humans, sent them into a worried frenzy as minutes bled into hours and the sun remained covered by the moon. There was talk of the end of the world, of countless other theories fueled by despair during the prolonged hours of darkness.

For three days, Day and Night slept, and the eclipse remained.

* * *

The sunlight on his skin has always felt familiar to Katsuki, a constantly sharp awareness of the sun. This time, however, as he's dragged out of sleep, that feeling is weak—numbed, as if it were coming from far away.

His entire body feels light when he sits up, dislodging a weight from his waist with the movement. Disoriented, Katsuki looks to his left. The weight had been Shouto's arm; Shouto himself is still sleeping, but even if he looks calm, there's something wrong.

 _Everything_ seems wrong.

Shouto is paler than usual, and his body keeps blurring in Katsuki's vision, as if he weren't quite so solid. The glimmer in his wings is dim. And then there's the sounds and the smells and the heat of the sun, all of them muffled to Katsuki's senses.

"What the fuck happened," Katsuki mutters. There's something despairing about this feeling of being disconnected, like he's one step away from disappearing. " _What did you do to us?"_ he screams, but his rage falls on deaf ears—the universe doesn't reply.

A bird flies towards the tree, landing on one of the lowest branches. Katsuki stares at it and it stares back, cocking its head for a moment before flying away. Somehow, Katsuki feels like it's mocking him.

 _You thought you could defy the rules. You brought this on yourself._

Beside him, Shouto continues to sleep.

Getting up on shaky legs, Katsuki stumbles to the edge of the mountain, and his eyes widen at the chaos of the city below. He might not be able to hear well, but his sight is enough for him to realize that there's too much movement, too much agitation for the first hours of dawn. People roam the streets, pointing at the sky, the rumble of voices distant to Katsuki's ears.

Katsuki's palms sting where his nails dig into them. His memories are fuzzy, but he remembers the pull of sleep getting stronger with every passing hour as he and Shouto pushed against their instincts, he remembers it was also dawn as they lay on the grass and everything suddenly turned black.

Looking at the city, Katsuki realizes this can't be the same day. He slept for a lot more than a few minutes.

He wants to scream, to curse nature and its rules, but it's clear that screaming won't be of any help. Instead, Katsuki stalks back to the tree, kicking at the bark with an angry groan before sitting down next to Shouto.

"Guess I have to wait until sunset, huh," he says, letting his head fall back against the tree.

For hours, Katsuki waits, watching the sun make its way across the sky with frustrating slowness. His strength returns bit by bit, his connection to the world grounding him and making him feel like himself again. At some point, he lets his left hand fall on the grass, brushing against Shouto's as if to guarantee he's still there. He hasn't moved one inch since Katsuki woke up.

It's only when the sun starts dipping below the horizon that Shouto stirs.

Katsuki's mind is already drifting, but he startles awake when Shouto sits up. He doesn't have to ask to know that the same feeling that plagued him before plagues Shouto too—it's obvious by the way Shouto extends his hands in front of him, examining them with a frown before turning to Katsuki with eyes still hazy from sleep.

"It'll get better in a few hours," Katsuki says. "It was the same for me."

Shouto's posture tenses, understanding dawning on him. Katsuki watches as his jaw locks, his hair falling over his eyes and knuckles turning white when he closes his hands into fists.

It's good to know he's not the only one pissed off with the unfairness of it all, but still—

"Not like we can fucking change how the universe works," Katsuki says. It's the conclusion he came to during the afternoon, but hell if he's going to leave it at that. "We'll just have to make sure it doesn't get _that_ mad at us again," he adds.

Shouto's head whips up, expression slowly changing from anger to amusement. Katsuki smirks at him before suppressing a yawn.

"You'll have to sleep soon," Shouto says.

Katsuki nods.

"Better wait a few weeks before pushing it agai—"

Before Katsuki can finish speaking, Shouto leans forward, sliding his hand to Katsuki's nape and pulling him into a kiss. There's something desperate about the way he keeps pressing closer, and Katsuki momentarily wonders if it has something to do with his senses being dulled.

Soon he forgets to worry about it, Shouto's mouth moving to his neck and sucking so hard he's sure there'll be bruises later. A groan escapes Katsuki's lips, and he needs all his willpower to keep his eyes from sliding shut—he doesn't want to risk it, not yet.

It doesn't take long for their clothes to be thrown aside. Maybe it's the sun disappearing in the horizon or the rush in every kiss—every touch—but it all feels like a fever dream, Shouto's skin getting slick with sweat beneath his hands, his taste on Katsuki's tongue when he bites down on his shoulder.

Shouto is a solid weight over his body. Katsuki clings to him, gasping when Shouto's fingers slick slip into him, and Shouto swallows the sound with another kiss. Even as the clock races against them, he's careful. There's gentleness in his touch even if he's desperate, even if he's leaking onto Katsuki's stomach and chanting breathless moans into his ear. Shouto takes his time preparing him, carding the fingers of his free hand through Katsuki's wings until Katsuki's mind is nothing but a fog of pleasure and he's snapping at Shouto to _hurry up_.

"I don't want to hurt you," Shouto says.

Katsuki can't help but huff at his own words being thrown back at him.

Shouto laughs, but doesn't make him wait much longer. They moan in unison when he enters him, and Shouto stills for a few seconds—Katsuki is painfully aware of his cock twitching inside him, and he wants nothing more than to tell Shouto to fucking _move_ —but before he can say anything, Shouto takes hold of his legs, fingers digging into Katsuki's thighs as he hoists them around his waist and _finally_ does.

"Shouto," Katsuki groans, resisting the urge to close his eyes. He doesn't want to succumb to the darkness yet—he just needs to fight it a little longer.

His gaze locks with Shouto's. His wings are open behind him, almost blending in with the sky, and Katsuki can't help but wound his arms around Shouto's back to settle his hands at the base of the feathers.

Shouto's next thrust falters and he lets his head fall on Katsuki's shoulder, speeding up his movements. Katsuki meets him halfway, arching his back and crying out as Shouto slams into him repeatedly, and even though he can feel his orgasm building up he dreads the moment when everything will end.

He doesn't want his time with Shouto to run out, but it's inevitable.

Shouto is the first to come, his thrusts turning shallow as he rides out his orgasm. He blindly reaches down to stroke Katsuki's cock, and his touch is all it takes to drive Katsuki over the edge, white hot pleasure flashing in front of his eyes as he spills onto his stomach.

Shouto finally lets Katsuki lower his legs, but he doesn't move from his place on top of him. Instead, he pulls him into another kiss—this one much softer, slow where the others had been hurried, longing where the others had been desperate. His clean hand moves soothingly over Katsuki's left thigh, almost apologetic as he traces the place he'd been digging his fingers into.

With the last dregs of energy leaving Katsuki's body, exhaustion catches up to him. The sky above them is filled with stars when they part; Katsuki blinks sleepily up at Shouto, loosening his hold around him as his eyes close.

The last thing he feels is the press of Shouto's lips on his forehead.

* * *

There was a time when Day and Night defied nature itself.

Instinct told them to stay apart—they didn't listen. What started as one single night of breaking the rules evolved into something more, something neither of them had seen coming, and they were punished for it.

But Day and Night had always been stubborn.

They couldn't have all the time in the world. They couldn't disappear. But they didn't want to go back to the start, to only the brief moments they were allowed together—so they wouldn't.

And now, every once in a while, humans find themselves in a day that lasts for a few more hours than it should, a night that stays even after dawn. They don't happen frequently, but when they do, it's like the sky is at a standstill for a moment, blues and purples mixing with oranges and reds.

And unseen to the human eye, Day and Night soar over the city. They talk and laugh and kiss at the top of the mountain, fighting their instincts and ignoring the rules.

Everything for one more moment together.


End file.
